1. Field of the Invention
The present invention relates to an image transmission method by an error retransmission mode.
2. Related Background Art
In a prior art facsimile apparatus having an ECM function, an image signal is transmitted by a high speed modem such as V.17, V.29 or V.21ter and a protocol signal representing a partial page is transmitted by a low speed modem such as V.21.
For the image signal, a protocol signal is added when a punctuation of a physical page on the transmitting station or one page of information exceeds one block (one block=245 frames, one frame=256 bytes).
However, when it is assumed that ten sheets of information each having 30 frames as one page of physical page information are to be transmitted without error at a transmission rate after the establishment of pre-protocol of 28.8 (kb/s), the time required per page is 30.times.256.div.28800.congruent.0.27 (sec), the time for training is 0.2 sec, for example, and the time for the protocol is approximately 2 sec so that a total time of 2.47 seconds is required. Accordingly, when ten sheets are transmitted, it requires 24.7 seconds. However, the actual transmission time of the image signal is approximately 2.7 seconds for the ten sheets and the time required for the protocol signal is wasted.